FIG. 1 shows a detail from a known damping valve 1 of a vibration damper. A valve body 3 has a stepped opening 5 for receiving a preloading spring 7 which acts on a tension rod 9 at which a valve disk 11 is arranged.
At least one flow channel 13 which connects a flow-in orifice 15 at one valve body side 17 to a flow-out orifice 19 at an opposite valve body side 21 is connected paraxially to the stepped opening 5. The flow-out orifice 19 is at least partially closed by the aforementioned valve disk 11.
The stepped opening 5 adjoins a guide channel 23 for the tension rod 9. The guide channel 13 leads into the flow-out orifice 19. The diameter of the guide channel 23 is comparatively large such that the tension rod 9 can assume a certain inclined position. This inclined position ensures that a certain friction force acts on the tension rod 9 to prevent the tension rod 9 from swiveling during a lifting movement of the valve disk.
In principle, this constructional form has the advantage that the areas in which gas bubbles can form between the component parts, namely the preloading spring 7, are under a higher pressure than on the flow-out side 19. Therefore, gas inclusions in the damping medium have hardly any effect on the damping force.
There is known from U.S. Pat. No. 2,941,629 a hydraulic shock absorber in which a valve body is preloaded in a closing position by a spring force on the one hand and a damping force is applied against an opening movement of the valve body on the other hand. In all of the disclosed embodiments, the preloading spring acting on the valve body is arranged on the low-pressure side of the damping valve, i.e., the damping device is arranged on the flow-out side of the damping valve.
This construction suffers from the functional drawback that gas enclosed in the damping medium can outgas on the low-pressure side and can therefore reduce the damping action of the damping valve.